Laminated magnetic core and method of making



Oct. 12, 1948 J. A. COMSTOCK 2,451,202

LAMINATED MAGNETIC CORE AND METHOD OF MAKING Filed Feb. 21, 1945 7 1: 4INVENTOR. I

' Q AW Patented Oct. 12, 1948 LAMINATED MAGNETIC CORE AND METHOD OFMAKING James A. Comstock, Clyde, N. Y., asslgnor, by mesne assignments,to Acme Electric Corporation, a corporation of New York ApplicationFebruary 21, 1945, Serial No. 579,128

My invention relates in general to transformer or reactor cores and inparticular to the design and method 01 forming E-shaped laminations.

It is an object 01' my invention to construct a laminated core, having asmall gap between the end of the center arm and the end piece, bypunching both the E-shaped lamination and the end piece from a strip orsheet metal, thus conserving material.

Another object 01' my invention is the process of constructing from astrip of sheet metal, an E-shapedlamination, having a recess on at leastone side edge of the center arm, and an end piece having a recess on oneside by punching rectangular openings to form the recesses and blankingthe end piece, thus forming the arms of the E-shaped laminations.

Another object of my invention is to provide an air gap core for areactor by having a gap between the center arm of an E-shapedlamination, and the end piece.

Another object of my invention is to provide an air gap core for areactor by having a gap between the center arm of an E-shaped laminationand the end piece, the gap being formed by a recess in the side edge ofthe end piece adjacently disposed at the end of the center arm.

A further object of my invention is to form from a strip of sheet metal,an E-shaped lamination and an end piece, the end piece being formed frommaterial between the arms of the E-shaped lamination. v

Other objects and a fuller understanding of my invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

Figure 1 is a layout of the strip of sheet metal showing the progressiveformation 01' the E- shaped lamination and end piece;

Figure 2 is a view of the end piece as it is punched from the materialbetween the center arm and aside arm of the E-shaped lamination;

Figure 3 is a layout of one complete lamination showing the relativeposition of the E-shaped lamination and the end piece;

the same as the length of the base of the E-shaped 3 Claims. (01.175-356) lamination I. As the strip of metal progresses through the die,the holes I! located for fastening means are punched. Also thesubstantially rectangular shaped openings ii are punched. These openingsH are located to become the recesses II 'in the center arm and therecess I! in the end piece. The recess in the center arm is locatedsubstantially intermediate the ends of the arm, thus also locating therecess l1 substantially intermediate the ends of the end piece. Afurther operation, as the strip progresses through the die, is theblanking of the two end pieces l5, thus forming the arms of the E-shapedlamination. In blanking these end pieces the cutting line between thecenter arm and the end piece divides the opening H, thus the recess i3and the recess H are substantially equal in width. The formation of therecess in the center arm prevents slivering during the blankingoperation. The strip of sheet metal i0 is then out along the cuttingline l8, thus severing the lamination from the strip. Since the arms ofthe E-shaped lamination illustrated in Figure 3 have equal length, thegap between the-end of the center arm and the adjacent side edge of theend piece is formed by the recess ii.

In the blanking operation two end pieces are constructed, but only oneis used. The extra end piece may be used in the construction of otherlaminated cores. The only waste is the material Irom the openings H andthe fastening holes. The elimination of one of the slots H in the stripI0 results in E-shaped lamination l8 as illustrated in Figure 5. Thelamination I8 is a modiflcation oi the lamination H, the modificationresulting from having a recess is on only one side of the center arm. Itis apparent that other modifications may be made without going beyondthe scope of the invention.

Figure 4 is a perspective showing the relation of several laminations toeach other in a laminated core. The drawing is an exploded view of asection of the laminated core.

In the prior art, the usual procedure is to provide a uniform air gap,which in the case of E-I type laminations results in three air gaps, oneat the center leg and also an air gap at each outer leg of the Elamination. This results in stray .flux emanate from the outer legs ofthe laminachanges the electrical characteristic of the unit accusesDescribing the purpose briefly. my invention embodies two main ieatures.One is a design that provides a strapless punching means and the I othera construction which makes possible an air gap in the center leg only ofan -1 lamination design. Therefore, the stray flux is confined aroundthe center core leg, thus resulting in a reduction in losses andhum'level which are ob- Jectionable for the reasons outlined above.

Although I have described my invention with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of theinvention as hereinaiterclaimed.

I claim as my invention:

1. The method of constructing E-shaped laminations and endpiecelaminations -from a strip of material in the successive steps ofpunching spaced elongated openings in the strip of material, punchingendpiece laminations from the strip of material with a part of theelongated openings disposed in and thereby forming air gap recesses in aside edge of theendpiece laminations, and cutting the E-shapedlaminations from the strip of material with the remainder of the ing anelongated opening in the strip of material, punching the endpiecelamination from the strip of material with a part of the elongatedopening disposed in and thereby forming an air gap recess in aside edgeof the endpiece lamination, and cutting the E-shaped lamination from thestrip of material with the remainder of the elongated opening disposedin one leg of the E- shaped lamination.

3. In a laminated core, an E-shaped lamination having a base and havingside arms and a center arm of equal length with an edge 01' one of-saidarms having a recess ,therein, and an endpiece lamination having a sideedge abutting against the ends of the side arms of the E-shapecllamination and having an air gap recess in said side edge positioned toform an air gap between said center leg of the E-shaped lamination andsaid endpiece lamination, each of said laminations having fiat surfaceson each side thereof, said endpiece lamination having dimensionssubstantially equal to the dimensions of the open space between two nextadjacent arms of the E- shaped lamination.

JAMES a. COMSTOCK.

/ REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,477,359 Johannesen- Dec. 11,1923 1,782,521 Trombetta Nov. 25, 1930 1,783,050 Morrill Nov. 25, 19301,819,481 Pearson Aug. 18, 1931 1,876,451 Gurtler Sept. 6, 19322,333,995 Gaynor Nov. 9. 1943

